Over the years I've tried all the above except crunching down the .307 cases. I do think the .307 is the best donor for a resize effort but with brass getting more available I didn't bother.
I resized some .30-30 cases for the .303 and about a third of them showed small splits on the first firing. I knew a guy in Texas that just used straight up .30-30 rounds and forced them into the chamber. He died of cancer so that didn't get him but not something I'd dream of doing.
Handloading is the only way to go if you really like to shoot more than once a year.
